China's military drills around Taiwan in response to the US house speaker's visit to the self-ruled island is a disproportionate and unjustified escalation, US Secretary of State Antony Blinken said today.

Blinken said the US has made it repeatedly clear to China that it does not seek a crisis, adding that Washington and its allies were seriously concerned by its latest actions.

China has been conducting the largest-ever military exercises in the Taiwan Strait, including launching live missiles around the island it claims as part of its sovereign territory.

"There is no justification for this extreme, disproportionate and escalatory military response," Blinken told a news conference on the sidelines of an Asean meeting, adding, "now, they've taken dangerous acts to a new level."

He emphasised that the US would not take action to provoke a crisis but it would continue to support regional allies and conduct standard air and maritime transit through the Taiwan Strait.

"We will fly, sail and operate wherever international law allows," he said.

Blinken is in Cambodia meeting counterparts from Southeast Asian and 27 other countries, including China, Japan, Britain, the European Union and India. He did not meet with his Chinese counterpart Wang Yi.

Asean, which is hosting the gathering, earlier called for restraint from all sides and said there was a risk of miscalculation and conflict between major powers.

Earlier today, China announced it would sanction US House Speaker Nancy Pelosi in response to her "vicious" and "provocative" actions in visiting Taiwan.

Blinken said Asean and other Asian officials were seriously concerned that China’s moves would destabilise the entire region.

"The last thing that countries in the region want is to see differences between mainland China and Taiwan...to be resolved by force," Blinken said after today's East Asia Summit.

"It is incumbent upon us and China to act responsibly. What we don't want is efforts by any country, including China and Russia, to disrupt international peace and security," he said.

- Reuters